Allow setting sockstreambuf buffer size and max putback

[kSkip]

I would like to use the sockstreambuf with a larger buffer size, and think it would be nice to adjust the max put back as well. In addition, I also changed the buffer pointers to unique_ptr. I figured that was just pre-C++11 code.

[kSkip]

For here, should this be out_buffer + out_buffer_size? Because epptr is defined as "one past the end of the put area". If I understand this correctly, the effective buffer size will be 1 char smaller if we use out_buffer_size-1

[davisking]

Yeah epptr() is one past the put area, but the final allocated byte is deliberately excluded from that put area because this implementation uses it to hold the character that triggered overflow(). So it's fine, it's just a matter of how the other parts of the code define it.

[kSkip]

Cool, thanks for explaining. I find the std::streambuf interface really confusing sometimes.

[davisking]

Yeah it's somewhat bizarre

[davisking]

Looks good. I just fixed std::unique_ptr<char> needing to be std::unique_ptr<char[]> and pushed some cleanup stuff. Once all the tests run I'll merge it :D

Thanks for another PR.

[kSkip]

I just fixed std::unique_ptr<char> needing to be std::unique_ptr<char[]>

Oh, good catch. Thanks for the help.